The Impact of Ferromagnetic Order on Second Harmonic Generation in Monolayer CrPS4

In a groundbreaking study led by Professor Sheng Zhigao at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, the phenomenon of strong nonlinear magnetic second harmonic generation (MSHG) induced by ferromagnetic order in monolayer CrPS4 was observed for the first time. This discovery holds significant implications for the field of optoelectronics.

Second harmonic generation (SHG) is a nonlinear optical effect that is sensitive to symmetry breaking in materials. While SHG has traditionally been observed in crystals with broken symmetry (i type), its presence in magnetic systems (c type) has been limited by its weak intensity. This limitation has hindered the potential applications of magnetic two-dimensional van der Waals materials in optical devices.

The research team led by Professor Sheng delved into the magnetic order-related SHG effects in the two-dimensional antiferromagnetic material CrPS4. They discovered that in bulk and even-layered CrPS4, the antiferromagnetic order did not exhibit any significant c type SHG effects. However, in odd-layered CrPS4, a substantial c type SHG effect induced by monolayer ferromagnetic order was observed for the first time.

This observation of ferromagnetic order induced c type SHG effects in a 2D magnet represents a significant breakthrough in the field of nonlinear optics. The dual breaking of spatial and time inversion symmetries in monolayer CrPS4 resulted in a signal strength comparable to that of i type SHG, which arises from the breaking of crystal structural symmetry. This unique characteristic sets monolayer CrPS4 apart from other magnetic materials.

The discovery of strong nonlinear magnetic second harmonic generation induced by ferromagnetic order in monolayer CrPS4 has promising implications for the development of advanced optical devices. By understanding the relationship between SHG and magnetic order in 2D materials, researchers can further explore the potential of monolayer CrPS4 in optoelectronics applications.

The findings of this study shed light on the previously unexplored nonlinear optical properties of two-dimensional van der Waals materials. The observation of ferromagnetic order induced c type SHG effects in monolayer CrPS4 opens up new avenues for research in the field of nonlinear optics and optoelectronics.